#include <cstdio>
#include <iostream>

int main()
{
    //向标准输出打印的----文件描述符1
    std::cout << "hello cout" << std::endl;
    printf("hello printf\n");

    //标准错误---2
    std::cerr << "hello cerr" << std::endl;
    fprintf(stderr,"hell fprintf\n");
    return 0;
}